Piping systems are prevalent throughout our everyday world. Most of us think of piping systems as underground structures used to convey liquids of one sort or another. To the novice, the concept of pipeline installation underground sounds relatively straight forward: a) dig a trench b) lay the pipe in the trench, and c) fill the trench back in. While this simplified perspective of pipeline construction may be appealing, it does not begin to address the concepts involved in the underground installation of a pipeline.
The installation procedure consists of trench floor preparation, providing a sufficiently stable working platform, and meeting the design grade requirements. Following pipe placement, backfill material which has been selected with regards to potential material migration, required density, depth of cover, weight of soil and surcharge loads must be considered. Sealing and securing pipe ends to prevent contamination during installation and when piping is unattended is also required.
A particularly difficult step in larger pipe installation is connecting pipe sections at the joints. Seamless pipe with a factory-installed gasket requires specific steps to be followed to ensure proper installation and performance of the pipe:
1. Clean bell and spigot. Both bell and spigot must be free of any dirt or foreign matter to ensure proper sealing between the gasket and the bell surface. The compressed gasket is moving along the bell interior; therefore, cleaning of the interior bell surface is critical. The spigot must be cleaned to beyond the reference mark.
2. Check the gasket. Make sure that the gasket has not been twisted, turned or damaged in any manner. If the gasket is missing, install a replacement gasket on the spigot.
3. Lubricate the bell. The entire inside circumference of the bell should be covered with a thin film of lubricant. Do not lubricate the spigot end on the gasket. Apply the lubricant with a cloth, sponge, glove or brush.
4. Align pipes before joining. Pipe assemblies can be made by hand; by using a bar and block, lever pullers or hydraulic jacks; or, if necessary, a backhoe bucket, but only with great care. If using a backhoe, place a 4″×4″ [100 mm×100 mm] board or plank between the backhoe bucket and the edge of the pipe. The backhoe operator will not be able to see if the assembly is complete, so a helper should be located at the joint to signal when proper assembly occurs. Do not apply force directly to the edge of the pipe. It is good practice to lay pipe with bells forward (upstream) so you will pull the spigot into the bell; brace the bell end while you carefully push the spigot end into the bell up to the reference mark on the spigot. Upon completion of the joint, the reference mark should be flush with the bell end of the pipe and remain visible. Do not assemble the joint beyond the reference point. Over-assembly of the joint could damage the bell of this or adjacent pipe—the joint may lose its flexibility and leak, or the spigot may squeeze down into the neck of the bell and thereby reduce the pipe's internal diameter. The fixtures taught herein will improve pipe installation methods and pipe joint integrity.
Also, when contaminated piping is decommissioned, the surfactant used to immobilize internal contamination can off-gas or leach and damage the environment. Ends of pipe sections must be sealed against liquid or gas excursions prior to storage. Fixtures taught herein will enable safe pipe decommissioning of all types of piping materials including metal and plastic.